Plug and socket arrangements for transmission lines have long been used in telephony, and audio equipment, as well as in high frequency transmission lines such as seen in television and data processing work station systems.
In telephony and audio equipment, plug and jack arrangement have long been known wherein the plug may be long or short and have two or three or more axially spaced conductor elements which engage complex arrangements of cantalever sprung contact elements in the jack or socket, and wherein some of these contact elements in the socket may operate to make or break connections when displaced by the plug element. In some cases the system is such that a short plug is used for one kind of apparatus, such as a microphone, and a long plug for another kind of apparatus such as a tape unit, for example, and the contact elements in the jack automatically make the appropriate connections.
For high frequency transmission systems, the transmission lines have been divided into distinct classes, such as coaxial cable, twisted pair, shielded twisted pair, and twin-x. There have been developed for each of these high frequency wiring systems particular kinds of connectors, and when an equipment is to receive either of two different kinds of cables it has been customary to provide two jacks or sockets in the equipment, each unique to the type of cabling system the plug of which it is to receive.
Thus, although various connector systems have been known, some of which accommodate different length plugs or cause internal switching action to take place as aforesaid, there has remained an unsatisfied need for a practical connector system having a jack which will receive a standard coaxial plug such as a BNC coaxial cable plug and, in the alternative, a plug for a shielded or unshielded wire pair transmission vehicle, an moreover a need for such a hybrid arrangement wherein the jack will respond automatically to make appropriate transition from unbalanced electrical scheme of the coaxial cable to a balanced system such as usually used in the wire pair arrangement.